Electrical Conduction Mechanism Analysis of Epoxy Resin/Microcapsule Self-Healing Composites Based on Experiment and Random Distribution Model

As the core material of microcapsules, dicyclopentadiene (DCPD) has higher conductivity than epoxy resin matrix. When preparing epoxy/DCPD microcapsules with self-healing properties, the incorporation of DCPD may result in a decrease in the overall conductivity of the composite, potentially increasing the risk of thermal breakdown. In order to further investigate this phenomenon, the preparation of epoxy resin/microcapsule composites and their self-healing and electrical conductivity were studied in this article. First, DCPD microcapsules were prepared by in situ polymerization method to prepare epoxy resin/DCPD self-healing composites. The self-healing ability of cracks was verified by scanning electron microscopy (SEM) and macroscopic observation. Second, the effects of microcapsule content and particle size on the conductivity of composites were systematically studied, and it was found that the addition of microcapsules increased the conductivity of composites. Further experimental and finite element (FE) simulation results show that the conductivity of the composite increases gradually with the increase of microcapsule content. The conductivity of 25 vol% microcapsules is 5.3 times that of 5 vol% and 18 times that of pure epoxy resin. When the volume fraction of microcapsules is the lowest, the influence of particle size on the overall performance is not significant. Conversely, when the volume fraction rises substantially and the particle size exceeds the specified threshold, a slight decrease in conductivity can be observed. By studying the distribution of five typical microcapsules on the zx plane, the influence mechanism of microcapsule distribution on the conductivity of the composite was discussed. It was found that the conductivity of the microcapsule connecting channel parallel to the current direction was about 2.5 times that of the microcapsule connecting channel perpendicular to the current direction. The research in this article provides an important reference for understanding the formation mechanism of microencapsulated composites and provides a theoretical basis for the optimization design and application of epoxy resin/microencapsulated composites in the future.